For readers who have ever had the sneaking suspicion that they're being shafted, the latest book from this Pulitzer Prize-winning investigative team ( America: What Went Wrong? ) provides the facts, figures, names and anecdotes to prove it. Their goal is to show how all those abstract terms bandied about on the Sunday morning talk shows affect the average taxpayer, particularly anyone whose family income is between, say, $25,000 and $150,000. Wealthy individuals squirrel away money through tax-free bonds, charitable-donations deductions and racehorses, among other write-offs; and the wealthiest corporations benefit from foreign tax credits, deductions for estimated worth of brand names and even the writing-off of interest on loans taken out to pay their stockholders (Weren't stockholders supposed to share both profits and losses?). All of which, the authors note with jackhammer regularity, leaves Joe and Jane Shmoe holding the tab. The authors are bipartisan in their apportionment of blame, rounding up not only the usual Republican presidential suspects but also Democrats like LBJ (whose ``unified budget'' amounted to a grand-scale doctoring of the books), Dan Rostenkowski (superannuated Chairman of the House Ways and Means Committee) and even independent Ross Perot (whose tax-free income in 1991 was somewhere between $18 and $87 million). Their ``modest proposal'' on reforming the tax system is indeed that: one based largely on eliminating deductions and making all income--no matter how earned--equally taxable. Barlett and Steele's greatest achievement, though, is to have painstakingly translated mountains of often deliberately obscure material, thereby making their book a dream for those who've never quite grasped what government, corporations and the wealthiest few are doing--and a nightmare for those who have and want to keep that knowledge to themselves. (Mar.)